Previously, there is known a fuel injection device that can inject high pressure liquid fuel. For example, in a fuel injection device disclosed in the patent literature 1, three tubular members are coaxially arranged one after another and are joined together by welding to form a housing. A fuel passage, which conducts the fuel to be injected, is formed in an inside of the housing.
In the fuel injection device of the patent literature 1, among the three tubular members, which form the housing, two tubular members, which are located at two ends, respectively, of the housing, are made of a magnetic material, and an intermediate tubular member, which is interposed between the two tubular members, is made of a non-magnetic material. A coil is placed on a radially outer side of the intermediate tubular member and a stationary core. With this construction, when the coil is energized, a movable core can be magnetically attracted to the stationary core.
In the fuel injection device of the patent literature 1, when a pressure of the fuel in the fuel passage is increased to a predetermined value or higher, the housing may possibly be deformed in a radial direction. Particularly, when an area around any one of connecting portions, at which the three tubular members are respectively joined, is deformed in the radial direction, a stress may be concentrated at this connecting portion to possibly cause fracturing of the welded portion and generation of a gap between the tubular members. When the gap is formed between the tubular members, the fuel in the fuel passage may possibly leak to an outside of the housing.